Optical coherence tomography system

Abstract

The present disclosure provides an optical coherence tomography (OCT) system for characterising first and second areas of interest of a material. The OCT system comprises first and second optical elements in use positioned at the first and second areas of interest of the material. The first and second optical elements are at least partially transmissive for electromagnetic radiation. The system further comprises first and second scanning heads in use positioned at the first and second optical elements, respectively, to receive electromagnetic radiation that has interacted with the material at the first and second areas of interest. In addition, the system comprises at least one detector optically coupled to the first and second scanning heads. The first and second optical elements are arranged such that respective reference radiation associated with the first and second optical elements is generated by reflection at interfaces of or at the first and second optical elements, respectively, and the first and second optical elements are arranged or positioned such that an optical path length difference between the reference radiation associated with the first optical element reference radiation and electromagnetic radiation that interacted with the material associated with the first optical element differs from an optical path length difference between the reference radiation associated with the second optical element and electromagnetic radiation that interacted with the material associated with the second optical element.

The invention claimed is: 
     
       1. An optical coherence tomography (OCT) system for characterising first and second areas of interest of a material, the OCT system comprising:
 first and second optical elements in use positioned at the first and second surface areas, respectively, the first and second optical elements being at least partially transmissive for electromagnetic radiation; 
 a scanning system having first and second optical portions, the first and second scanning portions being positioned at the first and second optical elements, respectively, to receive electromagnetic radiation that has interacted with the material within the first and second regions; and 
 at least one detector optically coupled to the scanning system; 
 wherein the first and second optical elements are arranged such that respective reference radiation associated with the first and second optical elements is generated by reflection at interfaces of or at the first and second optical elements, respectively, and the first and second optical elements are arranged or positioned such that an optical path length difference between the reference radiation associated with the first optical element and electromagnetic radiation that interacted with the first region differs from an optical path length difference between the reference radiation associated with the second optical element and electromagnetic radiation that interacted with second region. 
 
     
     
       2. The OCT system of  claim 1  wherein the OCT system is arranged such that both the reference radiation and the electromagnetic radiation that interacted with the material associated with the first optical element and also both the reference radiation and the electromagnetic radiation that interacted with the material associated with the second optical element propagate along a common optical path towards the detector. 
     
     
       3. The OCT system of  claim 1  wherein the first and second optical portions of the scanning system are provided in the form of first and second scanning heads that are positioned at the first and second optical elements, respectively, to receive electromagnetic radiation that has interacted with the material at the first and second areas of interest. 
     
     
       4. The OCT system of  claim 1  wherein the first and second optical elements are arranged such that an optical length of a path of the electromagnetic radiation through at least a portion of the first optical element to an interface of or at the first optical element differs from that through at least of portion of the second optical element to an interface of or at the second optical element. 
     
     
       5. The OCT system of  claim 1  wherein each of the first and second optical elements comprises at least two layers of a material having different optical properties and wherein the OCT system is arranged such that the electromagnetic radiation that is reflected at an interface between two of the at least two layers of each optical element forms respective reference radiation. 
     
     
       6. The OCT system of  claim 1  wherein the first and second optical elements are arranged or positioned such that an optical path length of electromagnetic radiation that interacted with the material at the first optical element differs from that of the electromagnetic radiation that interacted with the material at the second optical element. 
     
     
       7. The OCT system of  claim 1  wherein the first and second optical elements have a non-uniform thickness. 
     
     
       8. The OCT system of  claim 1  wherein the OCT system is arranged to apply a mechanical load to the first and second areas of interest of the material. 
     
     
       9. A method for characterising a material, the method comprising the steps of:
 providing the material; 
 positioning first and second optical elements with first and second optical portions of an optical scanning system, respectively, 
 
       at first and second surface areas of respective first and second regions of interest of the material, the first and second optical elements being at least partially transmissive for electromagnetic radiation, and being arranged such that respective reference radiation associated with the first and second optical elements is generated by reflection at interfaces of the first and second optical elements, respectively, and the first and second optical elements are arranged or positioned such that an optical path length difference between the reference radiation associated with the first optical element and electromagnetic radiation that interacted with the material of the first region differs from an optical path length difference between the reference radiation associated with the second optical element and electromagnetic radiation that interacted with the material of the second region;
 optically coupling a detector to the scanning system; 
 directing electromagnetic radiation towards the 
 
       first and a second regions through the first and second surface areas, respectively; and detecting the electromagnetic radiation received by the optical portions of the scanning system. 
     
     
       10. The method of  claim 9  wherein the first and second surface areas are directly adjacent surfaces. 
     
     
       11. The method of  claim 9  wherein the first and second surface areas are spaced apart from each other. 
     
     
       12. The method of  claim 9  wherein one of the first and second surface areas is directly below another one of the first and second surface areas, respectively. 
     
     
       13. The method of  claim 9  wherein the first and second optical elements are joined elements. 
     
     
       14. The method of  claim 9  wherein the first and second optical portions of the scanning system are provided in the form of first and second scanning heads in use positioned at the first and second optical elements, respectively, to receive electromagnetic radiation that has interacted with the material at the first and second areas of interest. 
     
     
       15. The method of  claim 9  wherein the first and second optical elements are separate from the first and second optical portions of the scanning system and wherein the method further comprises positioning the first and second optical portions of the scanning system at the first and second optical elements, respectively, to receive electromagnetic radiation that has interacted with the material of the first and second regions of the material, respectively. 
     
     
       16. The method of  claim 9  wherein the first and second optical elements may form parts of, or are joined with the first and second optical portions of the scanning system, respectively. 
     
     
       17. The method of  claim 9  wherein the step of positioning a first and a second optical element at the first and second surfaces, respectively, is conducted such that the first and second optical elements contact the respective surface areas. 
     
     
       18. The method of  claim 9  comprising directing both the reference radiation and the electromagnetic radiation that interacted with the material of the first region and also both the reference radiation and the electromagnetic radiation that interacted with the material of second region propagate along a common optical path towards a detector. 
     
     
       19. The method of  claim 9  further comprising step of forming OCT images associated with material at the first and second regions simultaneously using the electromagnetic radiation received by the first and second optical portions and detected by the detector. 
     
     
       20. The method of  claim 9  further comprising applying a mechanical load through the first and second regions through the first and second surfaces, respectively.